Polio eradication certificate laudable, but the endgame is still tricky

Dateline

Almost 25 years ago, Sam Pitroda, then adviser to the prime minister chaired a meeting in Delhi in which it was decided to produce inactivated poliovirus vaccine (IPV) in India for inoculating children against the crippling disease that infected 500 to 1,000 children daily in the 1970s and 1980s.

The vaccine's inventor Jonas Salk convinced the top echelons of Indian government on the importance of going forward with IPV ignoring the Union Health Ministry's choice of oral polio vaccine.

Notwithstanding the cost factor – IPV is costlier than oral polio vaccine (OPV) – the government in March, 1988 decided to set up a vaccine manufacturing unit named Indian Vaccine Company Limited (IVCOL) to make IPV as large number of kids were affected and killed by the polio virus. Land was acquired at Manesar, ahead of Gurgaon and French vaccine producer Institut Merieux was roped in.

As the health ministry was against the idea and refused to license the IPV except for research purpose, the government decided to set up the Rs 90 crore manufacturing unit as a public sector undertaking supported by the newly created department of biotechnology, which was to provide Rs 20 crore and Indian Petrochemicals Limited, which too promised Rs 20 crore. The rest was to come from the French partner.
But suddenly in January 1992, the government without any consultation with the scientific community decided to discontinue with the IPV plan and closed down the IVCOL. “The World Health Organisation advised developed countries to use IPV and asked the poor nations to go with OPV. Developing countries were taken for a ride as there were clear serological evidence to suggest OPV was not as effective as IPV,” said Pushpa Mitra Bhargava, founder director of Centre for Cellular and Molecular Biology, Hyderabad.

More than two decades later as India completes three years without a single polio case and is set to receive a polio-free certificate from the World Health Organisation, the question on the two decade old vaccine choice returns to haunt the policymakers.Even though IPV is the only weapon to eradicate polio from India, when and how to introduce the IPV in the national programme remains a key question as introduction of IPV in the endgame strategy has its own pitfalls. 

There are two types of vaccines to tackle polio. In 80 per cent cases, the paralysis is permanent and some of the children die. The oral polio vaccine created by Albert Sabin contains a live and attenuated virus that does not cause the disease in majority of kids. The IPV on the other hand contains an inactivated form of the virus.

Cause of concerns

The polio virus exist in nature in three types designated as type 1, 2 and 3. While type-2 was eliminated from in India in 1999 and from the world in 2000, it was the type 1 and 3 virus, which were the cause of concerns in India. For IPV, the three inactivated polio virus strains are mixed whereas for OPV, the three vaccines are given as liquid drops.

India, which at one point of time had the world’s highest polio burdens, spent upwards of  Rs 12,000 crore on polio eradication since 1995, took almost three decades to succeed. The last polio case (type-1) was reported from West Bengal on January 13, 2011. Three years had gone by under the careful watch of the government and a battery of public health workers to ensure the point of no return for polio.

“The next tactic is to introduce IPV in routine schedule, with one dose at about the time of 3rd dose of DPT/OPV. We have yet to decide two issues: (1) what if we cannot get high coverage in states with low DPT 3 coverage? Will we need to give IPV by campaigns like we did with measles immunisation? (2).how many IPV doses? one is minimum but is one enough?” wondered T Jacob John, a former professor of Christian Medical College, Vellore and one of India's foremost experts on polio.

Ideally India would add a dose of IPV to its routine immunisation programme by end-2015 latest, in keeping with the time lines of the global polio endgame, said Bruce Aylward, assistant director general in the World Health Organisation, who is in charge of global polio eradication.

“The best version of IPV to be produced in India is definitely the Sabin-IPV as it is the safest in terms of productions. WHO has worked with to establish a technology transfer programme and platform for Sabin-IPV and a number of Indian producers have already been selected for tech transfer,” he said.

But there is a Catch 22 situation. The oral vaccine in rare cases can cause vaccine associated paralytic polio. A more common problem is vaccine-derived polio virus (VDPV) that regains virulence through mutations and spread like the wild one. India had 21 VDPV cases in 2009, five in 2010 ad seven in 2011. Last year, there were 5 VDPV cases in India, out of which one died.

Polio can be eradicated completely only when VAPP and VDPV cases are eradicated. This is difficult to achieve as OPV has to be discontinued first to stop VAPP. Without any OPV, the circulating VDPV cases that are kept under control by the OPV will spread and cause outbreaks. It’s a Hobson's choice for the policymakers as eradication means no polio virus.

“VDPVs are a risk to a global polio free world. But an essential part of the polio endgame strategy is to begin phasing out the OPV strains to eventually eliminate the risk of VDPVs altogether,” said Aylward.